Saitama is a superhero who became so just for fun. After three years of “special” training, he has become so strong that he is virtually invincible. In fact, he is too strong – even his strongest opponents are taken with a single fist and it turns out that being devastatingly strong is actually a kind of boredom. With his passion for being a lost hero along with his hair, but still meeting new enemies every day, how much longer can he keep it?